Fuel Tank Selector Valve Leaking

[79Scott]

Hey Guys,
Any reason why the fuel tank selector valve would be leaking gas? I filled up the right side fuel tank the other day and when I pulled into the garage gas was running down the frame rail. It appears the selector valve has a built in drain?

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[dvdswan]

I'm not sure what the piece is in the picture, but if its leaking I would replace the valve and with the years of age I would replace all the hoses too. 3/8" and 5/16" IIRC.

 

[80BrownK10]

There was a similar thread a few months ago. I forget what the thought was.

When I fill my right tank and put it up full it does the same sometimes too. I am not sure if it's fuel running back from a bad check valve or if it's pressure from temp change and a very full tank?

I don't know exactly how it works and have not have not had mine out to look at it.

I will also say mine leaks out of that same barbed metal tube. It's clearly designed to do that, or else that would not be there. Mine does not run done the frame rail though.

 

[Dmack]

IIRC, that is a vent for the valve. If it is leaking, the valve needs to be replaced.

 

[Jalopy_J]

Not sure why the valve has that vent on it, but if fuel is running out of it, it's leaking. Unfortunately they aren't made anymore. I need one too.

 

[MrMarty51]

I converted My 78 over to the motorized valve and with that began setting it up for a TBI conversion.
All I now need is a set of fuel tanks from an 87 and the fuel pump/sender units and I`ll be good to go.
Unfortunately, it does take the addition of some extra wires.
Fuel gauge on Mine was working then it just quit for some reason. I have not yet tested the left side tank to see if that gauge works.
I do have the dash unit with the electronic speedo and a couple of options, either a TBI or a Port unit.

 

[79Scott]

Thanks guys, I may just replace it Napa and Rockauto have them.

 

[Wumbo]

Thanks guys, I may just replace it Napa and Rockauto have them.

I bought the AC Delco valve from Rockauto, it was a drop in replacement.

As stated, replace the hoses since you're there. I believe they are 1/4, 5/16, and 3/8

 

[75gmck25]

Unless something has changed recently, Rock Auto and other suppliers only have the 3 port Pollack valve, and you have the older six port valve with one switching terminal. The six port valve switches both the fuel feed line and the return line, and the vent lines are just t'd together. I think that is why many have decided to use the newer motorized valve as a replacement, but its wiring is different.

Bruce

 

[Dmack]

Not sure why someone said they aren't made anymore. It is the standard six port with the five wire harness connector. I put a new one in last month from napa.

 

[75gmck25]

The six port valve with a five wire harness is still available. However, AFAIK the six port Pollack with a single 12 volt connector (used on earlier trucks) is no longer available. Since the OP has a '78 truck, it should have used the older wiring and valve. IIRC, the old style six port valve I found at the pick and pull was on an '81 truck, but I don't know when they switched to the newer valve.

If you have an older single terminal solenoid you will need to do quite a bit of new wiring to use a newer six port valve. Its probably not that hard to rewire, but I don't really know.

Bruce

 

[MrMarty51]

The six port valve with a five wire harness is still available. However, AFAIK the six port Pollack with a single 12 volt connector (used on earlier trucks) is no longer available. Since the OP has a '78 truck, it should have used the older wiring and valve. IIRC, the old style six port valve I found at the pick and pull was on an '81 truck, but I don't know when they switched to the newer valve.

If you have an older single terminal solenoid you will need to do quite a bit of new wiring to use a newer six port valve. Its probably not that hard to rewire, but I don't really know.

Bruce

It does require some new wires to be run from under the dash to the fuel selector valve.

 

[Snoots]

Anyone have an electrical schematic on this?

 

[bucket]

Not sure why someone said they aren't made anymore. It is the standard six port with the five wire harness connector. I put a new one in last month from napa.

Because the earlier 6-port valve with a single wire hookup is seemingly unavailable.

 

[Dmack]

Because the earlier 6-port valve with a single wire hookup is seemingly unavailable.

I was aware of that, but the pic that was posted appeared to be the five wire, newer style.